Exhaust device having deflection plates

ABSTRACT

An exhaust device having deflection plates comprises a cabinet that is provided with a space therein. An opening is formed in front of the cabinet. The air-extraction hood located at the top of the cabinet is provided at the bottom thereof with an elongate air-extraction slot facing downwards and parallel to the rear plate. A left deflection plate is vertically located in the space in a manner of being relatively oblique to the left lateral plate while a right deflection plate is vertically located in the space in a manner of being relatively oblique to the right lateral plate. Thereby, the air drawn towards the elongate air-extraction slot can flow into the cabinet via the left and the right deflection plates so as to prevent the leakage of pollutants from the opening in front of the cabinet.

TECHNICAL FIELD

The present invention relates to an exhaust device having deflectionplates, and more particularly, to an exhaust device that has deflectionplates used for guiding the airflow in the cabinet so as to prevent theleakage of pollutants and is suitable for the cabinets in factories andlaboratories and the exhaust cabinets in commercial kitchens.

BACKGROUND

For performing the function of a conventional exhaust cabinet, a shelterplate with an opening is provided on the upper end of a cabinet, and aflow-guide plate is vertically placed in the rear of the cabinet, wherethe flow-guide plate is provided with a specially designed opening.Through the opening of the shelter plate and the opening of theflow-guide plate in the rear of the cabinet, harmful gas can be drawnout by using an air-extraction machine and ducts. When the exhaustcabinet is used, the air-extraction machine should be operatedcorrespondingly in order to continue air extraction. During this moment,the door of the cabinet should not be closed completely or an openingshould be provided at the doorsill in advance in order to preventburning of a motor resulting from failing to supply air. Besides, whenin use, it is usually necessary to open the door of the cabinet to anapproximate height to facilitate operators stretching their hands intothe cabinet for experimental operations. However, when the door of theconventional exhaust cabinet is open, based on the principles ofAerodynamics, harmful gas within the cabinet may escape easily aroundthe peripheries of the door. Moreover, the leakage may be even severerwhen operators are opening or closing the door, or stand in front of theopen cabinet for experimental operations, or when there are ambientdrafts or there are people walking by. The main reason of the leakage isthat vortex and turbulence are easily formed around the peripheries ofthe cabinet door and around operators' chests. The vortex and turbulencemay result in the mass and momentum exchange between the inside and theoutside of the cabinet. Therefore, the leakage of the pollutants in thecabinet is scarcely avoidable. Unfortunately, there is nearly noconventional exhaust cabinet can be used without opening and closing itsdoor. In other words, operators can operate their experiments only whenthe cabinet is open. Besides, the exhaust cabinet is scarcely placed inthe environment where there is no ambient air turbulence or there are nopeople walking by. As a result, in the laboratories, factories, orbuildings using the conventional exhaust cabinets, people usually smellthe sour odor emitted from chemicals because pollutants continue leakingfrom the cabinets. Operators and people working thereby may get used tothe odor and long-term chemical pollution occurs.

In order to solve the leakage problem resulting from using aboveconventional exhaust cabinet, an oblique dual air curtain exhaustcabinet has been developed as shown in FIGS. 13 and 14. An opening isrespectively provided in front of and in back of the cabinet “a”.Besides, an air blow part (b, b1) is respectively provided in front ofand in back of a bottom plate of the cabinet “a”. Through the two airblow parts (b, b1), air jets are blown upwards in oblique directionsopposite to each other. An air-extraction hood “c” is provided in thespace above the bottom plate. The air-extraction hood “c” is providedwith an air-extraction part “c1”. The air-extraction part “c1” isparallel to the two air blow parts (b, b1). Besides, the air-extractionpart “c1” is located just above and between the two air blow parts (b,111). Thereby, when the air-extraction part “c1” draws in air while theair blow parts (b, b1) blow air, two oblique air curtains (d, d1)flowing from bottom towards top can be formed in order to exhaust thepollutants confined between the two oblique air curtains.

According to the structure of the dual air curtain exhaust cabinet, thefront and the back sides of the cabinet are respectively formed an openspace for operators to perform operations, whereas the left and theright sides thereof are enclosed in order to confine harmful gastherein. In practical use, the two ends of each elongate air blow part(b, b1) should be spaced from the left and right lateral plates (e, e1)in a certain distance (f, f1) so as to supply fresh air in. However,because the left and the right lateral plates (e, e1) are completelyenclosed ones, experimental results show that unsteady vortex willappear in the cabinet after the air flows in respectively through thegaps between the two ends of the air blow parts (b, b1) and the left andright lateral plates (e, e1). Consequently, airflow will partially flowout through the two gaps so as to result in the leakage of harmful gas.

In order to overcome above shortcomings, inventor had the motive tostudy and develop the present invention. After hard research anddevelopment, the inventor provides an exhaust device having deflectionplates, which is capable of preventing effectively the leakage ofpollutants so as to ensure the safety in use.

SUMMARY OF THE DISCLOSURE

An object of the present invention is to provide an exhaust devicehaving deflection plates, where an elongate air-extraction slot isprovided on the bottom of the air-extraction hood, and a left and aright deflection plates are provided in the space beneath the cabinet soas to exhaust high-temperature pollutants or soot effectively andprevent the leakage of the pollutants or soot.

Another object of the present invention is to provide an exhaust devicehaving deflection plates, where an elongate air blow part is provided infront of the bottom plate of the cabinet, and a left and rightdeflection plates are respectively provided in air-supply spaces locatedat the left and right sides of the elongate air blow slot, so as toconfine the airflow inside the cabinet and prevent the leakage ofpollutants.

Another object of the present invention is to provide an exhaust devicehaving deflection plates, where a guiding plate is respectively providedat the front ends of the left and right lateral plates, and a guidingpart is provided on the bottom of the front plate, so as to let airflowsmoothly flow into the cabinet and reduce the size of the backflow areain order to decrease the possibility of pollutants' leakage.

In order to achieve above objects, the present invention provides anexhaust device having deflection plates, comprising a cabinet, a leftdeflection plate, and a right deflection plate. The cabinet includes anair-extraction hood, a bottom plate, a left lateral plate, a rightlateral plate, and a rear plate, all of which define a space. An openingis provided in front of the cabinet. An air-extraction part is providedat the bottom of the air-extraction hood. The air-extraction part has anelongate air-extraction slot facing downwards and the elongateair-extraction slot is parallel to the rear plate. The air-extractionpart is connected with an air-extraction machine for drawing airupwards. The left deflection plate is vertically located in the space ina manner of being relatively oblique to the left lateral plate, so as toform a first included angle between the left deflection plate and theleft lateral plate. The right deflection plate is symmetrical to theleft deflection plate and is vertically located in the space in a mannerof being relatively oblique to the right lateral plate, so as to form asecond included angle between the right deflection plate and the rightlateral plate. Thereby, it is able to guide the airflow in the cabinetand prevent its leakage.

In practice, the front end of the left deflection plate is in a positionclosely against the right lateral surface of the left lateral plate. Thefront end of the right deflection plate is in a position closely againstthe left lateral surface of the right lateral plate. Besides, the firstand the second included angles face towards the rear plate.

In practice, a curved first guiding part is provided at the bottom ofthe front end of the air-extraction hood, while a curved second guidingpart is provided at the top of the front end of the bottom plate.Moreover, a curved first guiding plate is provided at the front end ofthe left lateral plate of the cabinet, while a curved second guidingplate is provided at the front end of the right lateral plate of thecabinet for guiding airflow flowing into the space.

In practice, an elongate air blow part is provided in front of thebottom plate. The elongate air blow part has an elongate air blow slotwith an opening facing vertically upward or obliquely upwards forblowing air jets vertically and upwards or in a direction towards therear plate of the cabinet. A first air-supply space is formed betweenthe left end of the elongate air blow part and the left lateral plate. Asecond air-supply space is formed between the right end of the elongateair blow part and the right lateral plate. The elongate air blow slot isparallel to the elongate air-extraction slot so as to form a nearlytwo-dimensional oblique air curtain between the elongate air-extractionpart and the elongate air blow part during the air-extraction machine isin operation.

In practice, the exhaust device having deflection plates according tothe present invention alternatively comprises a cabinet, a front and arear left deflection plates, and a front and a rear right deflectionplates. The cabinet includes an air-extraction hood, a bottom plate, aleft lateral plate, and a right lateral plate, all of which define aspace. An opening is respectively provided in front of and in back ofthe cabinet. An air-extraction part is provided at the bottom of theair-extraction hood. The air-extraction part has an elongateair-extraction slot facing downwards and the elongate air-extractionslot is perpendicular to the left and right lateral plates. Theair-extraction part is connected with an air-extraction machine fordrawing air upwards. The front and rear left deflection plates arerespectively vertically located in the space in a manner of beingrelatively oblique to the left lateral plate, so as to form a firstincluded angle between the front and the rear left deflection plates andthe left lateral plate. The front right deflection plate is symmetricalto the front left deflection plate, while the rear right deflectionplate is symmetrical to the rear left deflection plate. The front andthe rear right deflection plates are respectively vertically located inthe space in a manner of being relatively oblique to the right lateralplate, so as to form a second included angle between the front and therear right deflection plates and the right lateral plate.

The following detailed description, given by way of examples orembodiments, will best be understood in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a front side cross-sectional view of a first embodiment ofthe present invention.

FIG. 2 shows a lateral side cross-sectional view of the first embodimentof the present invention.

FIG. 3 shows a topside cross-sectional view of the first embodiment ofthe present invention.

FIGS. 3A and 3B show another embodiment of the air-extraction hood ofthe present invention.

FIGS. 4 and 5 show the use of the first embodiment of the presentinvention.

FIG. 6 shows a lateral side cross-sectional view of a second embodimentof the present invention.

FIG. 6A shows a lateral side cross-sectional view of the presentinvention where a movable cabinet door is installed.

FIG. 7 shows a topside cross-sectional view of the second embodiment ofthe present invention.

FIGS. 8-10 show the use of the second embodiment of the presentinvention.

FIG. 11 shows the use of a third embodiment of the present invention.

FIG. 11A shows a lateral side cross-sectional view of the presentinvention where an air blow device is provided on the bottom of themovable cabinet door.

FIG. 12 shows a topside cross-sectional view of a fourth embodiment ofthe present invention.

FIG. 13 shows a front side cross-sectional view of a conventionalair-curtain type exhaust cabinet.

FIG. 14 shows a lateral side cross-sectional view of the conventionalair-curtain type exhaust cabinet.

DETAILED DESCRIPTION

Please refer to FIGS. 1-3 showing a first embodiment of an exhaustdevice having deflection plates 1, which comprises a cabinet 2, a leftdeflection plate 3, and a right deflection plate 4.

The cabinet 2 is in substantially rectangular or square shape. The lowerpart of the cabinet 2 is provided with a storage cabinet 29 for storagepurpose. The storage cabinet 29 has legs and is able to support thecabinet 2. The cabinet 2 has an air-extraction hood 21, a bottom plate22, a left lateral plate 23, a right lateral plate 24, and a rear plate26. After being assembled together, above components define a space 27within the cabinet 2. An opening 251 is provided below the front end ofthe air-extraction hood 21. Besides, a curved first guiding part 252 isprovided at the bottom of the front end of the air-extraction hood 21,and a curved second guiding part 226 is provided at the top of the frontend of the bottom plate 22. The front ends of the left lateral plate 23and the right lateral plate 24 in the cabinet 2 are respectivelyprovided with a curved first guiding plate 231 and a curved secondguiding plate 241. Thereby, it is able to reduce the degree ofturbulence and agitation produced when air is drawn into the opening251. In implementation, the first guiding part 252, the second guidingpart 226, the first guiding plate 231, and the second guiding plate 241can be in a shape of a quarter arc of a circle or of a curved surfacehaving a large curvature radius, both of which are capable of producingairflow-guiding effect.

The air-extraction hood 21 is provided with an air-extraction part 211on its bottom. The air-extraction part 211 has an elongateair-extraction slot 212 facing downwards. The elongate air-extractionslot 212 is substantially rectangular. The elongate air-extraction slot212 is lengthwise parallel to the rear plate 26. A plurality of airexhaust outlets 213 is provided on the top of the air-extraction hood21. Each air exhaust outlet 213 is connected to an air collector 214 andthe air collector 214 is connected with an air-extraction device 215.Thereby, when the air-extraction device 215 is in operation, theelongate air-extraction part 212 is capable of drawing in air andguiding the air in the cabinet 2 to flow upwards. In implementation, theair-extraction device 215 can be a drawing fan, air blower, or otherfluid mechanisms capable of extracting air. Moreover, the bottom 216 ofthe air-extraction hood 21 is provided with a liquid barrier frame 217.The liquid barrier frame 217 protrudes upwards from the surface of thebottom plate 216 and surrounds the peripheries of the elongateair-extraction slot 212. A liquid collector 218 is provided below therear end of the bottom plate 216 of the air-extraction hood 21.Alternatively, the liquid collector 218 also can be provided below thefront end or the lateral end of the bottom plate 216.

In implementation, the air-extraction hood 21 also can be asubstantially L-shape casing. As shown in FIG. 3A, the elongateair-extraction slot 212 faces downwards and obliquely at an angle.Alternatively, as shown in FIG. 3B, the elongate air-extraction slot 212faces in a direction away from the rear plate 26.

The left and right deflection plates 3, 4 are respectively a rectangularupright plate. The left deflection plate 3 is vertically located in thespace 27 in a manner of being relatively oblique to the left lateralplate 23. Besides, the front end of the left deflection plate 3 is in aposition closely against the right lateral surface of the left lateralplate 23, so as to form a first included angle θ1 between the leftdeflection plate 3 and the left lateral plate 23. The first includedangle θ1 faces towards the rear plate 26. The right deflection plate 4is symmetrical to the left deflection plate 3. Besides, the rightdeflection plate 4 is vertically located in the space 27 in a manner ofbeing relatively oblique to the right lateral plate 24. Besides, thefront end of the right deflection plate 4 is in a position closelyagainst the left lateral surface of the right lateral plate 24, so as toform a second included angle θ2 between the right deflection plate 4 andthe right lateral plate 24. The second included angle θ2 also facestowards the rear plate 26.

As shown in FIGS. 4 and 5, when any item or facility on a countertop isof a heating apparatus 9 that will produce high-temperature pollutantsor soot (such as a heating furnace or a heating plate), thehigh-temperature pollutants or soot will move upwards due to buoyancyeffect inherent of high-temperature gas. When the air-extraction device215 is in operation, the high-temperature pollutants or soot can bedrawn upwards into the air-extraction slot 212. Consequently, externalair in front of the cabinet 2 can be drawn into the cabinet space 7 viathe opening 251. The airflow can be guided by the left deflection plate3 and the right deflection plate 4, so as to form closely-juxtaposedsteady vortex pairs (as shown in FIG. 4) that is capable of carrying thehigh-temperature pollutants or soot steadily and upwards and exhaustingit via the air-extraction slot 212. When airflow flows along the rightlateral surface of the left lateral plate 23 and the left lateralsurface of the right lateral plate 24 of the cabinet 2, the airflowflowing into the cabinet 2 will not flow back to the original entranceopening 251 by means of the hindrance and the guidance of the left andright reflection plates 3, 4. As a result, it is able to prevent theleakage of high-temperature pollutants or soot.

Please refer to FIGS. 6 and 7 showing a second embodiment of an exhaustdevice 1 having deflection plates. This embodiment differs from thefirst embodiment in following aspects: where a front plate 25 is furtherprovided below the front end of the cabinet 2; the opening 251 isprovided below the front plate 25; and the first guiding part 252 is asemicircular bar that is provided at the internal side of the bottom ofthe front plate 25. Alternatively, in implementation, as shown in FIG.6A, the front plate 25 has a lateral part overlapped with a movablecabinet door 255; the first guiding part 252 is provided at the internalside of the bottom of the movable cabinet door 255; and the movablecabinet door 255 is slidable upwards and downwards relative to the frontplate 25 in order to control the opening degree of the movable cabinetdoor 255. In addition, an elongate air blow part 221 is provided at thefront side of the bottom plate 22 of the cabinet 2. A first air-supplyspace 222 is formed between the left end of the elongate air blow part221 and the left lateral plate 23. A second air-supply space 223 isformed between the right end of the elongate air blow part 221 and theright lateral plate 24. Besides, the elongate air blow part 221 has anelongate air blow slot 224 and the elongate air blow slot 224 isparallel to the elongate air-extraction slot 212. Moreover, the elongateair blow part 221 is in communication with an air blower 225. By meansof the function performed by the air blower 225, a two-dimensional airjet can be blown vertically upward or obliquely upwards via the air blowslot 224. In implementation, through the air blow slot 224, atwo-dimensional air jet also can be blown towards the rear plate 26 ofthe cabinet 2. The air blower 225 also can be replaced by a crossflowfan or other fluid mechanisms.

By this way, as shown in FIGS. 8-10, the air-extraction device 215 andthe air blower 225 can be in operation simultaneously so as to have theair blow slot 224 blow air jet upwards and to have the air extractionslot 212 draw in the air jet. As a result, air can be supplied throughthe first air-supply space 222 and the second air-supply space 223.Besides, the left deflection plate 3 and the right deflection plate 4can be used to guide airflow so as to form a nearly two-dimensionaloblique air curtain 8 between the elongate air blow slot 224 and theelongate air-extraction slot 212. Thereby, it is able to carry upwardsinto the above air-extraction hood the pollutants confined between theoblique air curtain 8, and the rear plate 26, the left and the rightlateral plates 23, 24 of the cabinet 2. These pollutants eventually canbe exhausted via the air collector 214.

Please refer to FIG. 11, in which is shown a third embodiment of anexhaust device 1 having deflection plates. In this embodiment, astrip-shape air blow device 253 is provided at the bottom, either insideor outside the cabinet, of the front plate 25. The strip-shape air blowdevice 253 draws the fresh air outside the cabinet and blow the drawnair downward so as to enhance ability of preventing leakage ofpollutants or high-temperature soot. In implementation, two air blowdevices 253 can be provided respectively at two ends of the bottom ofthe front plate 25. Alternatively, as shown in FIG. 11A, when thelateral part of the front plate 25 is overlapped with a movable cabinetdoor 255, the air blow device 253 is provided at the bottom of themovable cabinet door 255.

Moreover, FIG. 12 shows a fourth embodiment of an exhaust device 1having deflection plates 31, 32, 41, and 42. In this embodiment, twoopenings 251, 253 are respectively provided in front of and in back ofthe cabinet 2. In other words, the two openings pass through the cabinet2. In the space 27, a front and a rear left deflection plates 31, 32 arerespectively provided in a manner of being relatively oblique to theleft lateral plate 23, and a front and a rear right deflection plates41, 42 are respectively provided in a manner of being relatively obliqueto the right lateral plate 24. A first included angle θ1 is formedbetween the front and the rear left deflection plates 31, 32 and theleft lateral plate 23. A second included angle θ2 is formed between thefront and the rear right deflection plates 41, 42 and the right lateralplate 24. Besides, the front right deflection plate 41 is symmetrical tothe front left deflection plate 31 while the rear right deflection plate42 is symmetrical to the rear left deflection plate 32. Thereby, it isable to prevent the leakage of pollutants or high-temperature soot fromthe front or the back of the cabinet 2 so that users can conductexperiments or cook food in front or in back of the cabinet 2.

Therefore, the present invention has following advantages:

-   1. According to the present invention, the left and right deflection    plates not only can be used to guide airflow to ensure air supply    and to prevent the air entering the cabinet from flowing backwards,    but they also can be used to guide effectively the airflow in the    cabinet. Thereby, it is able to exhaust the pollutants or    high-temperature soot effectively and to reduce the leakage of the    pollutants.-   2. According to the present invention, air can be smoothly guided by    utilizing the first guiding plate, the second guiding plate, the    first guiding part, and the second guiding part, so as to reduce the    backflow occurring when the air is drawn into the opening. Thereby,    it is able to prevent the pollutants or high-temperature soot from    being carried out of the opening by the backflow.

As disclosed in the above description and attached drawings, the presentinvention can provide an exhaust device having deflection plates forreducing effectively the leakage of pollutants or high-temperature sootso as to ensure the safety in use. It is new and can be put intoindustrial use.

Although the embodiments of the present invention have been described indetail, many modifications and variations may be made by those skilledin the art from the teachings disclosed hereinabove. Therefore, itshould be understood that any modification and variation equivalent tothe spirit of the present invention be regarded to fall into the scopedefined by the appended claims.

1. An exhaust device having deflection plates, comprising: a cabinet,having an air-extraction hood, a bottom plate, a left lateral plate, aright lateral plate, and a rear plate, all of which define a space,where an opening is provided in front of the cabinet; an air-extractionpart is provided at a bottom of the air-extraction hood; theair-extraction part has an elongate air-extraction slot facingdownwards; the elongate air-extraction slot is parallel to the rearplate; and the air-extraction part is connected with an air-extractionmachine for drawing air upwards; a left deflection plate, verticallylocated in the space in a manner of being relatively oblique to the leftlateral plate, so as to form a first included angle between the leftdeflection plate and the left lateral plate; and a right deflectionplate, symmetrical to the left deflection plate and vertically locatedin the space in a manner of being relatively oblique to the rightlateral plate, so as to form a second included angle between the rightdeflection plate and the right lateral plate.
 2. The exhaust devicehaving deflection plates as claimed in claim 1, wherein a front end ofthe bottom of the air-extraction hood is provided with a curved firstguiding part while a top of the front end of the bottom plate isprovided with a curved second guiding part.
 3. The exhaust device havingdeflection plates as claimed in claim 1, wherein a front plate isfurther provided in front of the cabinet and the opening is formed belowthe front plate.
 4. The exhaust device having deflection plates asclaimed in claim 3, wherein an elongate air blow device is provided atthe bottom of the front plate for blowing air downwards.
 5. The exhaustdevice having deflection plates as claimed in claim 1, wherein anelongate air blow part is provided in front of the bottom plate; theelongate air blow part has an elongate air blow slot with an openingfacing upwards; a first air-supply space is formed between the left endof the elongate air blow part and the left lateral plate; a secondair-supply space is formed between the right end of the elongate airblow part and the right lateral plate; and the elongate air blow slot isparallel to the elongate air-extraction slot so as to form a nearlytwo-dimensional oblique air curtain between the elongate air-extractionpart and the elongate air blow part during the air-extraction machine isin operation.
 6. The exhaust device having deflection plates as claimedin claim 1, wherein a curved first guiding plate is provided at thefront end of the left lateral plate the cabinet and a curved secondguiding plate is provided at the front end of the right lateral plate ofthe cabinet for guiding airflow into the space.
 7. The exhaust devicehaving deflection plates as claimed in claim 1, wherein a front end ofthe left deflection plate is in a position closely against a rightlateral surface of the left lateral plate; a front end of the rightdeflection plate is in a position closely against a left lateral surfaceof the right lateral plate; and the first and the second included anglesface towards the rear plate.
 8. The exhaust device having deflectionplates as claimed in claim 7, wherein a front end of the bottom of theair-extraction hood is provided with a curved first guiding part while atop of the front end of the bottom plate is provided with a curvedsecond guiding part.
 9. The exhaust device having deflection plates asclaimed in claim 7, wherein a front plate is further provided in frontof the cabinet and the opening is formed below the front plate.
 10. Theexhaust device having deflection plates as claimed in claim 9, whereinan elongate air blow device is provided at the bottom of the front platefor blowing air downwards.
 11. The exhaust device having deflectionplates as claimed in claim 7, wherein an elongate air blow part isprovided in front of the bottom plate; the elongate air blow part has anelongate air blow slot with an opening facing upwards; a firstair-supply space is formed between the left end of the elongate air blowpart and the left lateral plate; a second air-supply space is formedbetween the right end of the elongate air blow part and the rightlateral plate; and the elongate air blow slot is parallel to theelongate air-extraction slot so as to form a nearly two-dimensionaloblique air curtain between the elongate air-extraction part and theelongate air blow part during the air-extraction machine is inoperation.
 12. The exhaust device having deflection plates as claimed inclaim 7, wherein a curved first guiding plate is provided at the frontend of the left lateral plate the cabinet and a curved second guidingplate is provided at the front end of the right lateral plate of thecabinet for guiding airflow into the space.
 13. An exhaust device havingdeflection plates, comprising: a cabinet, having an air-extraction hood,a bottom plate, a left lateral plate, and a right lateral plate, all ofwhich define a space, where an opening is respectively provided in frontof and in back of the cabinet; an air-extraction part is provided at thebottom of the air-extraction hood; the air-extraction part has anelongate air-extraction slot facing downwards; the elongateair-extraction slot is perpendicular to the left and right lateralplates; and the air-extraction part is connected with an air-extractionmachine for drawing air upwards; a front and a rear left deflectionplates, respectively vertically located in the space in a manner ofbeing relatively oblique to the left lateral plate, so as to form afirst included angle between the front and the rear left deflectionplates and the left lateral plate; and a front and a rear rightdeflection plates, where the front right deflection plate is symmetricalto the front left deflection plate and the rear right deflection plateis symmetrical to the rear left deflection plate; and the front and therear right deflection plates are respectively vertically located in thespace in a manner of being relatively oblique to the right lateralplate, so as to form a second included angle between the front and therear right deflection plates and the right lateral plate.